Poop Egg?

Today, like everyday I came home from work and checked the nest boxes. Of my four chickens only the RIR has layed through the cold months and sure to form she had laid one..... but in the other box there was a mass of what looked like poop. The biggest poop I've ever seen in.... no shell.... just a mass of goo... not yolk.... not white.... regular looking poop but the size of an egg.... could this be a sign that one of the others is practicing or preparing? Hope I haven't grossed ya'll out..... just need to hear your experiences....